Le potentiel de pêche du Nouveau-Québec

Les ressources piscicoles du Nouveau-Québec ont été exploitées depuis toujours par les Amérindiens (Indiens et Inuit) par la pêche de subsistance et la pêche domestique, pour lesquelles aucune statistique valable n'existe, mais dont on peut être sûr qu'elles n'ont pas affecté significativement les espèces touchées. Les deux dernières décennies ont vu la pêche industrielle et la pêche sportive surexploiter ponctuellement certains peuplements de poissons, particulièrement à la périphérie de la baie d'Ungava. Dans l'ensemble, cependant, le potentiel de pêche du Québec nordique demeure peu touché et la Convertion de la baie (de) James et du nord québécois, intervenue en 1975 entre les Indiens, les Inuit et les gouvernements du Québec et du Canada permet d'envisager que la gestion de ressources précaires mais volumineuses, en raison de l'étendue du territoire et de l'abondance des plans d'eau qu'il recèle, s'organisera dans des conditions exceptionnellement avantageuses, dans un esprit de conservation et dans le cadre d'une rationalité dont on connaît peu d'exemples et dont les populations autochtones récolteront les bons effets.The fishery resources of Nouveau-Québec have been used for centuries by the Amerindians (Indians and Inuit) through subsistence and domestic fishing activities, for which no reliable statistics are available but which did not significantly exploit the potential yield of any species. Over the last twenty years, commercial and sport fisheries have overexploited certains areas, specially along the shores of Ungava bay, but the total potential yield of northern Québec remains virtually untouched. The James bay Convention (1975) negociated by the Indians, the Inuit and the governments of Québec and Canada raises hopes for a rational management of this precarious resource, from which the amerindian population looks forward to deriving economical advantages and social benefits

The Thames : March

https://digitalcommons.library.umaine.edu/mmb-ps/2795/thumbnail.jp

Snapshot Mueller matrix polarimeter by wavelength polarization coding

International audienceWe present a new, to the best of our knowledge, experimental configuration of Mueller matrix polarimeter based on wavelength polarization coding. This is a compact and fast technique to study polarization phenomena. Our theoretical approach, the necessity to correct systematic errors and our experimental results are presented. The feasibility of the technique is tested on vacuum and on a linear polarizer

Systematic errors specific to a snapshot Mueller matrix polarimeter

International audienceSystematic errors specific to a snapshot Mueller matrix polarimeter are studied. Their origins and effects are highlighted, and solutions for correction and stabilization are proposed. The different effects induced by them are evidenced by experimental results acquired with a given setup and theoretical simulations carried out for more general cases. We distinguish the errors linked to some imperfection of elements in the experimental setup from those linked to the sample under study

Two-channel snapshot Mueller matrix polarimeter

International audienceWe describe a new setup for a snapshot Mueller matrix polarimeter (SMMP). It relies on the separation and orthogonal polarization of two light beams by a Wollaston prism located at the setup output. The simultaneous treatment of the two spectra allows an enhancement of accuracy for real-time measurements through reduction of the effects caused by random noise and systematic errors. Moreover, it gives insight into the nonuniform spectral response of the medium under study. Experimental results support the feasibility of the proposed technique

Factors affecting methylmercury biomagnification by a widespread aquatic invertebrate predator, the phantom midge larvae Chaoborus

MeHg biomagnification by the phantom midge Chaoborus in relation to MeHg concentrations in their prey and its migratory behavior was investigated in two Canadian Precambrian Shield lakes. Three Chaoborus species with contrasted migratory behavior were collected in a fishless and a fish-inhabited lake. All species accumulated MeHg through their ontogenic development. In the lake inhabited by fish, all instars of Chaoborus punctipennis displayed a marked migratory behavior and were unable to biomagnify MeHg, whereas in the fishless lake, Chaoborus americanus and Chaoborus trivittatus biomagnified MeHg. Reduced biomagnification capacity of C. trivittatus, the coexisting species living with C. americanus, was also ascribed to a progressive vertical segregation with age. Growth dilution, amount and type of prey items or trophic position could not explain the different patterns of biomagnification. Our findings demonstrate that the most common invertebrate predator of temperate planktonic food webs can biomagnify mercury, contrarily to previous reports

Les migrations féminines du milieu rural vers le milieu urbain au Burkina Faso : faits, causes et implications

Thèse numérisée par la Direction des bibliothèques de l'Université de Montréal